66 ZOOLOGY OF THE VOYAGE OF H.M.S. SAMARANG. 



from the hind margin numerous horny setae, or fine bristles, which are protruded through 

 the fissured suture of the shell, the use of which, however, I have been unable to ascertain. 



4. Bulla Voluta, PI. XVIII. Pig. 5. Quoy and Gairnard, Voy. de 1' Astrolabe, pi. 26. f. 33-35. 



Hab. China Sea, in mud and debris at ten fathoms. 



In Bulla Voluta the eyes are visible at the sides of the head, but the foot is narrow, 

 and without the usually swimming side lobes. It is extremely slow in its movements, and 

 is an inhabitant of deep water. Most of the specimens procured by us were dead shells, 

 being bored by some carnivorous mollusk, showing the number of its enemies. 



58. PLEUROBRANCHUS, Cuvier. 



1. PLELmoBEANCHUS luniceps, PI. XVIII. Fig. 6 a, b. Cuvier, Regne Anim. Plew. f. 6 a, b. 



We have given a coloured figure of this beautiful species, which is very remarkable for 

 its depressed, almost foliaceous body, and broad semilunar head. The proboscis is retractile 

 when the animal is lively, but is protruded to its full extent before death. The dorsal 

 tentacles are abruptly truncate at the ends, and the hind part of the mantle is produced 

 into a siphonal inflexion, which guides the water into the marginal groove between the 

 dilated foot and mantle, where the branchial plume is situated. 



NUDIBRANCHIATA. 



Among the naked-gilled Gasteropods with which the equatorial seas abound, there are 

 very many forms which are not referable to any hitherto recognized genera, but which the 

 industry of future years will demonstrate : the two types here named Bomella and Cerato- 

 soma are of this class, and drawings were made of some others ; the species of Scyllcea and 

 two species of Goniodoris we have likewise regarded as new. 



59. BORNELLA, Gray. 



Corpus elongatum, compressum, semipellucidum, postice acuminatum, ventriculo ramoso in appen- 

 dicibus dorsalibus estendens. Caput appendicibus duabus stellatis aut fimbriatis. Tentacula dorsalia 

 retractiba in vaginulibus ramosis. Appendices dorsales in serie unica ad utrumque latus corporis dispositse, 

 cyUndricse, curvatse, conicse, bifida^ trifidfe, aut simplices ; branchiae bipinnatse, appendicibus dorsalibus 

 exeuntes. Pes linearis, sulcatus. 



The authors proposed to found a genus for these mollusks and had them figured for that 

 purpose, but were anticipated by Mr. Gray, into whose possession the drawings had pre- 

 viously passed in their way from the Admiralty. 



